This plugin is super handy.
My only complaint is that it makes the menu section looks crowded. It adds those radio buttons and checkboxes all over the place and they're not aligned in a aesthetically good-looking way (e.g. padding and stuff) so they look "stuffed". Add to that the descriptive text beneath them which isn't that helpful anyway-- I think you should get rid of it.
I also suggest you hide the roles checkboxes by default until the user clicks the "By Role" radio button, because, obviously they're not needed when I select the other radio buttons.
You can also add a fourth radio "Everybody" which shows the menu item to everyone. Currently, this is done by selecting "By Role" and then leaving all roles unchecked. A bit confusing.
Finally, you can align those radios and checkboxes in a table-like layout (not using tables!) like having two (or three) options in each row, with fixed padding/spacing between each (something like a grid).
Hope to see something implemented soon :)